Laminated glass



Jan. 7, 1936. WATKINS 2,026,717

LAMINATED GLAS S Original Filed April 30, 1928 i gwuwntoz 660/ efiwaflfm I v 7 attomq pat n Jin. 7,1936 I 2,026,717

George 'B. Watkins, Toledo, Ohio, assignor to Libbey-Owens-Ford GlassCompany, Toledo, Ohio, a corporation of- Ohio I Applioation April30,1928, SerialNo.273,781 Renewed November 6, 1933 The present inventionrelates to laminated from which'most of the solvents have been relass. jl moved. An important object of the invention is to pro- As is generallyknown, laminated glass comvide a process for producing laminated glassprises two or more sheets of glass and one or more 5 wherein two or morethermo-plasticizers, having sheets of non-brittle material such as acellu- 5 preferably ,high boiling point; low vapor preslose ester sheet.The cellulose ester sheet is insures, are combined to produce a bindingliquid terposed in the sandwich between the glass adapted for use in thejoining of two or more sheets, and it is the non-brittle sheet whichgives laminations. l the non-shatterable qualitiesv to the composite vAnother object of the invention is to provide sheetproduced from thesandwich, that is, pro- 10 such a process wherein two or morelaminations vided the glass sheets are properly joined to.

are bonded together by the aid of a binding liqthe nonbrittle sheet. uidproduced by mixing two or more thermo- The present invention relatesparticularly to plasticizers, the resultant mixture preferably betheliquid or medium used to obtain the bond ing such that it can be appliedto the laminabetween the non-brittle sheet and the glass 15 tions andallowed to remain thereon for a relasheets; The term binding liquid isused theretively long time before the laminations are fore to designatethis liquid.

pressed together, without causing injury. In Fig. 2, the numeral l4designatesa receptacle Other objects and advantages of the invention' inwhich is contained'a bath of my improved bindwill become moreappai'ent'during the course of ing liquid l5. The non-brittle sheet I6is shown as 0 the following description when taken in connecbeing passedthrough the liquid in a manner as to tion with the accompanying drawing.become coated therewith. Obviously, the binding In the drawing whereinlike numerals are emliquid l5 can be applied in many other ways thanployed to designate like parts throughout the that of being dipped, andthis inventioncontemsame, v plates any and all ways of applying thebinding 25' Fig. 1 is a diagrammatic View illustrating the liquid to thenon-brittle sheet,glass sheets, or all formation of a skin on a sheet ofglass, of the sheets. Fig. 2 illustrates diagrammatically the appli- Toproduce the binding liquid, I make a mixture cation of my improvedbinding liquid to a nonof two or more thermo-plasticizers, each prefertbrittle sheet, ably having a high boiling point, low vapor pres- 30 Fig.3 is a fragmentary sectional view showing sure. I have found that sometypes of liquids the laminations before they are united, have anoticeable solvent action on a cellulose Fig. 4 is a view similar toFig. 3, except that a ester sheet at room temperatures, and in such,skin is used on the glass sheets, cases it is essential to join orpress the sheets to- Fig; 5 is a fragmentary sectional view of a. formgether promptly after such active solvents have 36 x of finished sheet,been applied. If 'the pressing together at the 6 is the same as Fig. 5,except that it shows laminations is not accomplished soon after the theuse of a seal, application of the active solvent, the celluloid Fig. 7is a diagrammatic representation of a has atendency to 130w which isobjectionable.

40 press that may be used, and I have also found that by the combinationof 40 Fig. '8 is a fragmentary sectional view of a two or morethermo-plasticizers, a mixture can sheet of so-called bullet-proof"glass. be produced capable of being used in'the manu- In Fig. 1, thenumeral Ill designates a sheet of facture of excellent laminated orcomposite; glass.

preferably transparent glass whose surfaces may As an example of amixture that I have used. I be ground and polished, or not, as desired.In mention that diamyl phthalate and dibutyl some forms of laminatedglass it is desirable to phthalate, when mixed together, give a bindingform a skin on the laminations, and as shown in liquid of excellentqualities. Although a fifty- Fig. 1, a spray gun or the like II is usedto spray fifty mixture of thesetwo works very satisfac'to or otherwiseapply a solution l2 on a surface of rily, anylvother amounts or percents can be used; the glass sheet, which solution forms a deposit andalso the addition of a third thermo-plasticizl3 thereon. The solution l2may be any preer,'or even more than three liquids can be mixed. ferredcomposition dissolved in a suitable sol- For instance, diethyl phthalatecan be addedto vent such as for instance a cellulose composition themixture above named, andlan excellent bindifiaterialr After the'coatingl3 hasbeen formed 'ing liquid produced. r on the sheet, it is'usuallydried to forma skin In a mixture formed from an equal percentage 66glass where a n'iulti-opening press is used. By a multi- -opening pressis meant a press Where a number of sandwiches may be pressedsimultaneously to produce a plurality of finished composite 10 sheets.If a liquid is used that is particularly active at room temperatures,the first sandwich may become affected adversely, while the remainingsandwiches are being formed and placed in the press.

' I, therefore/mix together thermo-plasticizers that will give aresultant mixture relatively inac-,

tive at room temperatures, and also thermo-plasticizers that haverelatively high boiling point, low vapor pressures. By using suchliquids in the .2 mixture the finished sheet will not be affectedadversely when subjected to summers' heat, etc.,

when the composite sheet is placed in actual use.

Thesolvents herein contemplated as the bond inducing medium are of thatstable character in the laminated sheet when the latter is in normal usethat any decomposition of the bond inducing medium or the expected ornatural decomposition of the cellulose ester plastic incident to thelapse of time and heat and light energywill' not be ma- 3 teriallyaccelerated. The solvents possess sufliciently low vapor pressure asto-minimize the tendency toward" bubbling within the sheet due to achange of state of the bond inducing medium by passing from the liquidto the vapor phase when 35 properly used. 1 Solvents may be employedwithin the spirit of the invention as long as the mixture possesses thedesirable characteristics of stability, high boiling point, and lowvapor pressure. Esters of phthalic 4o acids for example, have been foundto satisfactorily embq'dythe above characteristics. Itis obvious thatcertain solvents, having the characteristics above specified, incarrying out the principle of the invention may vary from one another indegrees of high boiling points and low vapor pressures, etc. By way ofillustration, in the practice of the invention as herein set forth,theboiling points of the solvents should preferably be above 350 F. andshould preferably not exceed one-half 50 the vapor pressure of .camphorat ordinary temperatures. Assuming the vapor pressure of camphor to be.4 mm.'of mercury at 68 F. or ordinary temperature, the vapor pressureshould preferablynot exceed .2 mm. of mercury at 68 F.

It has been demonstrated that solvents having the characteristics beforementioned and having a boiling point not lower, and a vapor pressure notexceeding that specified have produced satisfac; tory results. 5

After the non-brittle sheet 16 has been coated with the binding liquidl5, the sheet may be interposed between the glass sheets I! in Fig. 3-

to form asandwich. The sandwich may then be placed in a-press designatedin its entirety by the numeral I8 in Fig. 7, and is subjected to thecombined action of heat and pressure. It is preferred that the pressingaction be so controlled that all excess binding liquid be expelledduring the pressingoperation. IThe typeof press illustrated is asingle-opening press, but it is to be understood that my improved sheetcan be formed from a multi-opening press,\or in 'anyother manner.

In Fig. 4, the glass sheets l9 are each provided with a skin coating 20,while the liquid covered non-brittle sheet 2| is interposed between the"skin coated surfaces of the glass sheets. The

binding liquid may also be applied to the surfaces of the glass sheetsin Fig. 3 or the skins 20 on the sheets l9 in Fig. 4, as well as on thenonbrittle membrane. 7 e

Fig. 5 shows diagrammatically the sheet formed from the laminationsshownin Fig. 3; In

some instances it is desirable to protect the bond between thelaminations, and therefore a seal 22 may be used as shown in Fig. 6.

In Fig. 8' a different type of product is shown, which comprises threesheets of glass and two sheets of non-brittle material, all bondedtogether by the aid of my improved binding liquid.

- It is to be understood that the form of the invention herewith shownand described is to be taken as the preferred embodiment of the same andthat various changes in the shape, size and 40 arrangement of parts maybe resorted to without departing from the spirit of the invention or thescope of the subjoined claims.

I claim:

v1. As a new article of manufacture, a sheet of 15 laininated glassconsisting of two sheets of glass and an interposed non-brittle membranetreated with a mixture of esters of phthalic acid.

2. As a new article of manufacture, a sheet of laminated glassconsisting of two sheets of glass and an interposed non brittle membranetreated with a mixture of diamyl phthalateand dibutyl phthalate.

' GEORGE B. WA'I'EZNS.

